The invention pertains to a coated cutting insert wherein the flank face has improved wear resistance and the rake face has improved impact resistance.
The article entitled "The Microstructure Features and Cutting Performance of the High Edge Strength Kennametal Grade KC850" by Nemeth et al., (Proc. Tenth Plansee Seminar, Metalwerke Plansee A. G., Reutte, Tyrol, Austria, (1981), pp. 613-627, mentions that, " . . . by combining a high impact resistant rake face with a deformation resistant flank face of a coated insert, we can substantially increase edge strength without significantly altering wear resistance." This article describes the use of a cutting insert which has a substrate with binder enrichment on the rake surface and the bulk microstructure (or composition) on the flank surface.
U.S. Pat. No. 4,610,931, to Nemeth et al., (U.S. Pat. No. Reissue 34,180) describes a coated cutting insert wherein the substrate has binder enrichment on the rake face and the bulk substrate composition on the flank face of the substrate. None of the above-mentioned documents presents a coated cutting insert with a substrate wherein the substrate has a flank face with improved wear resistance due to a flank surface region with a higher hard phase (e.g., solid solution carbide and/or carbonitride) content and a rake surface region with a microstructure (or composition) different from that of the flank surface region and which provides improved impact resistance.